An article by Hongjie Xu et al., “Synthesis of novel sulfonated polybenzimidazole and preparation of cross-linked membranes for fuel cell application”, Polymer, Volume 48, Issue 19, 10 Sep. 2007, pages 5556-5564, discloses that sulfonated poly[2,20-(p-oxydiphenylene)-5,50-bibenzimidazole] (SOPBI), prepared by post-sulfonation reaction of the parent polymer, poly[2,20-(p-oxydiphenylene)-5,50-bibenzimidazole] (OPBI), may be used in membranes for fuel cells. Fuel cells are devices that convert chemical energies from fuels into electricity through chemical reactions and membranes are individual components separate from electrodes of the fuel cells.
Differently, electrolytic cells are electrochemical cells in which energies from applied voltages are used to drive otherwise nonspontaneous reactions and, as is disclosed in the international patent application publication No. WO 2008/035092 A1, are sometimes used in water treatment systems and methods, for example, to produce hypochlorite, such as sodium hypochlorite and potassium hypochlorite, for controlling levels of microorganisms in water circulation systems.
Currently, there are two main types of electrochemical oxidant generators. In the first type, the anode and cathode are separated physically by plastic mesh and there is no ion exchange membrane. The oxidant generated at the anode has the possibility to contact cathode and be reduced again. This reduces the efficiency of the electrolytic cell.
The second type has an ion exchange membrane, usually with a cation exchange membrane made of a sulfonated tetrafluoroethylene based fluoropolymer-copolymer such as Nafion®. The membrane increases the resistance, and when the target product is hypochlorite, chlorine gas is produced in the anode chamber and the hydroxide ions are produced in the cathode chamber. The products in the anode and cathode chambers cannot react inside the cell but need be treated outside of the system. This increases the potential exposure to chlorine gas, which is highly toxic.